As an example of a polymer having helical structure of rigid-rod shape, a polyglutamic acid comprising a long n-alkyl chain, for example, n-decyl group, has been reported by Watanabe, et al. (see Non-Patent Literature 1, Non-Patent Literature 2, Non-Patent Literature 3, Non-Patent Literature 4, etc.).
In addition, in this connection, it has been reported that in a polyglutamic acid comprising a long chain alkyl group of n-decyl group or longer, not only cholesteric liquid crystal property but also hexagonal columnar and smectic phases are observed.
Further, it has been also reported that some other rigid or semi-rigid polymers, which are cellulose, polyisocyanate, polysilane and wholly aromatic polymer, exhibit thermotropic liquid crystallinity and lyotropic liquid crystallinity, as well as the above polyglutamic acid.
As another example of a liquid crystalline polymer having rigid-rod helical structure as described above, which has a great dipole moment along main chains of the polymer due to hydrogen bond between amide groups in a molecule, a polypeptide has been known. As an example of a polymer whose main chains are oriented by means of application of electric field by utilizing this great dipole moment, poly(γ-benzyl-L-glutamate) has been known (see Non-Patent Literatures 5 to 7).
In addition, in Patent Literature 1, a compound of 4-ethylenyl-benzoyl-L-glutamic acid which is useful as an intermediate for producing a compound of N-[2-amino-4-substituted-[(pyrrolo or pyrido)[2,3-d]pyrimidinyl-alkyl]benzoyl]-L-glutamic acid having an inhibitory effect to a dehydrofolic acid reducing enzyme, has been disclosed.
Patent Literature 1: JP-A-6-25246
Non-Patent Literature 1: Macromolecules, 17, 1004 (1984)
Non-Patent Literature 2: Macromolecules, 18, 2141 (1985)
Non-Patent Literature 3: Mol. Cryst. Liq. Cryst., 164, 135 (1988)
Non-Patent Literature 4: Springer-Verlag, Berlin, Heidelberg, p. 99-108 (1994)
Non-Patent Literature 5: E. Iizuka, et al., Biochemica et Biophysica Acta, 175 (2), 457-459 (1969)
Non-Patent Literature 6: E. Iizuka, et al., Biochemica et Biophysica Acta, 243 (1), 1-10 (1971)
Non-Patent Literature 7: E. Iizuka, et al., J. Phys. Soc. Jpn., 34 (4), 1054-1058 (1973)